1. Field of the Invention
The present invention relates to a plasma reactor for processing a large-sized wafer. More particularly, the present invention relates to a plasma reactor constructed to have a chamber, a cathode assembly supported on a one side wall surface of the chamber in a cantilever form and supporting a substrate, and a baffle plate for discharging reaction gas. The baffle plate enables asymmetric arrangement of vents for discharging reaction gas and enables uniform discharge of exhaust gas even in the cathode assembly of an asymmetric structure, thereby improving the uniformity of plasma within the chamber and improving the uniformity of a substrate etching rate in an etching process, etc.
2. Description of the Related Art
In general, a large-sized wafer that is used for a semiconductor Integrated Circuit (IC) device or a glass substrate that is a main part used for Liquid Crystal Display (LCD), etc. forms several thin film layers on its surface and, by selectively removing only a portion of the thin film, forms a hyperfine structure of a desired form on the surface, thus forming a complex circuit or thin film layer. At this time, thin film manufacturing is implemented through many manufacturing processes such as a washing process, a deposition process, a photolithography process, a plating process, an etching process, etc.
The aforementioned various processes are mainly implemented within a chamber or reacting furnace that is a processing device for isolating a wafer or substrate from the external.
Among the aforementioned processes, particularly, the etching process is a process of removing target materials from a wafer surface through a chemical reaction of a plasma state by jetting reaction gas (i.e., CF4, Cl2, HBr, etc.) within the chamber or reacting furnace. The etching process selectively removes a portion not covered with photoresist using a photoresist pattern as a mask, thus forming a fine pattern on the substrate. Thus, it is of most importance to keep etching uniformity for the whole substrate surface.
Thus, to improve etching uniformity and prevent process badness, plasma formed within the chamber should be kept uniform and get in contact with the whole substrate surface.
However, in the conventional plasma chemical reactor, the cathode assembly is installed in a left/right asymmetric structure within the chamber because the cathode assembly supporting the substrate is supported in a cantilever form by a cathode support shaft installed at a one side wall surface of the chamber. So, the following problems occur.
The first problem is that, when reaction gas generated after plasma reaction, polymer, or particles are discharged below the chamber, it is obstructed by the cathode support shaft supporting the cathode assembly, thus disabling uniform effective discharge of exhaust gas along the periphery of the cathode assembly. The second problem is that, when reaction gas is discharged, it is obstructed by the cathode support shaft at one side and, because the reaction gas is non-uniformly discharged, plasma cannot be uniformly formed on a substrate surface, thus causing the non-uniformity of an etching rate in an etching process, etc.